Dynamics of plasma anti-Müllerian hormone concentrations before and after ovum pick-up in pure and crossbred Hokkaido native ponies.

Abstract

Anti-Müllerian hormone (AMH) is a stable endocrine marker of the ovarian reserve in mares and correlates positively with the follicular population. This study aimed to examine plasma AMH concentration dynamics during ovum pick-up (OPU) and evaluate their relationship with follicular responses in purebred and crossbred Hokkaido native pony mares. Ten mares underwent 26 OPU sessions, with blood collected at multiple time points ranging from 1 hr before OPU to 4 weeks after OPU. Plasma AMH concentrations were measured using a chemiluminescence immunoassay. AMH concentrations declined significantly (P<0.01) at 24 hr (1.94 ng/ml), 72 hr (1.48 ng/ml), 1 week (nadir, 1.27 ng/ml), and 2 weeks (1.54 ng/ml) post-OPU compared with the pre-OPU levels (2.25 ng/ml). The levels started to increase gradually after 2 weeks. Pre-OPU AMH positively correlated with the number of aspirated follicles (r=0.48, P<0.05). This study is the first to identify a significant reduction in plasma AMH levels after OPU, followed by recovery within 3 weeks in pure and crossbred Hokkaido native ponies.